Under ambient conditions which increase the operating temperature of an engine, engine power may decrease, thereby decreasing engine efficiency. Some vehicles, such as rail vehicles, may undergo tunneling operation in which the vehicle travels through a confined space, such as a tunnel. During tunneling operation, temperatures of various systems of the vehicle, such as an engine system and a cooling system, may increase. In some examples, the temperatures may increase substantially, leading to decreased power and overheating of the engine of the rail vehicle.
In one approach, heat rejection to the cooling system and tunnel may be reduced by adjusting an operating parameter such as engine exhaust gas recirculation (EGR) in response to an indication of tunneling operation. As an example, an engine EGR amount may be substantially or completely reduced. In such an approach, however, operation of a turbocharger in the engine may exceed a choke level, thereby decreasing turbocharger efficiency.